This time, I will talk about "clean paper (dust-free paper)" used in a "clean room" where dust is minimized and cleanliness is managed.
For customers who have been using our brand of clean paper "Staclean" (Sakurai Co., Ltd.) for many years, you might be thinking, "What’s the point now?" However, for those who are considering clean paper for the first time or have been using it for years without giving it much thought, we would be grateful if you could read to the end.
There seems to be something called 'clean paper' for cleaning instruments as well. Unfortunately, for those looking for that 'clean paper', this is not relevant to the current discussion, but since we have the opportunity, please join me to expand our knowledge if you have the time.
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1. Industries using clean paper
It has been about 40 years since our company (Sakurai Co., Ltd.) started selling clean paper under the brand name "Staclean."
At the time of its launch, the domestic semiconductor industry was in a growth phase, and domestic semiconductor manufacturers, along with surrounding equipment and parts manufacturers, were establishing manufacturing plants with clean rooms across Japan.
＊Clean rooms refer to environments where clean suits and gloves are worn, as shown in the image below, to minimize dust generation and manage cleanliness during operations.
Currently, the clean paper market is mainly focused on industrial clean rooms (semiconductors, electronic components), but it is also used in clean rooms related to pharmaceuticals and biotechnology.
2. What is clean paper (dust-free paper)? The birth of clean paper MADE IN JAPAN.
In the clean room where semiconductor chips smaller than a grain of rice are manufactured, how to minimize and manage invisible levels of "dust" is crucial for improving yield and increasing product reliability.
During the growth period of the semiconductor industry in the 1980s, there was a growing need to address the "paper dust and airborne particles" generated from paper used in clean rooms.
First, because paper dust is generated with ordinary paper (general paper, copy paper), synthetic paper using film-based substrates has come to be used.
Many of the products were primarily made of polypropylene (PP) base material, which contained a white powder called "pigment" to achieve whiteness. Although it had a smooth appearance, it was not low in dust generation.
While it was fine for writing notes and memos, it could not be used for the main copy at the time because the base material was sensitive to heat. Additionally, during offset printing, static electricity was generated, which made it difficult to work with.
If it had been a heat-resistant polyester film (PET) with electrostatic measures such as coating, those issues might have been resolved, but at that time, we were using a large amount of paper, so we couldn't disregard the cost. So it was decided that paper-based solutions were indeed better, and inquiries came to our company (Sakurai Co., Ltd.) asking if there was no paper that does not generate dust or if it could not be made.
Our company, which has dealings with paper manufacturers, has developed and started selling the paper-based clean paper "Staclean" containing acrylic resin from scratch through repeated trial and error.
3. The story of clean paper colors
At the beginning of the development of the clean paper "Staclean," there were no color specifications from customers, and it was progressing in white. As samples of prototypes were submitted, there were voices suggesting that "perhaps a color other than white would be better" in order to distinguish it from regular paper, and the light blue that is now the base color of "Staclean" was chosen.
Unfortunately, there are no official records explaining why blue was chosen (though there are internal rumors...). I speculate that pink and yellow were considered too flashy, leaving green or blue as the options, but since our company (Sakurai Corporation) has blue as its corporate color, that may have influenced the decision.
In Japan and Southeast Asia, Staclean was gradually adopted after its launch, and later, clean paper began to be sold by other companies as well. However, since our Staclean's blue color had already established the image of 'clean paper = blue', most clean papers still predominantly feature blue.
Our "Staclean" offers seven colors (blue, pink, yellow, white, green, orange, violet) for copying, in response to your request for color differentiation.
4. The story of clean paper sizes
The best-selling clean paper size at our company (Sakurai Corporation) is undoubtedly A4 size. This started with copy paper, and now A4 is also common for printer output (laser and inkjet).
We also had B series sizes (B5, B4) available, but in Japan, guidelines were established in the 1990s to standardize administrative documents as much as possible to A series sizes (A4, A3), and private companies followed this trend.
Internationally, A4 size is widely adopted, but in the United States, the letter size standard is used.
In the United States, the adoption rate of letter size seems to be high. The size is 8.5 inches wide × 11 inches in length, and when converted to millimeters, it is 216 mm wide × 279 mm long, which is slightly wider and shorter than A4.
I sometimes get inquiries like, "Do you have letter-sized clean paper?"
We do not stock letter-sized clean paper, but we offer custom cutting to your desired size, so please feel free to consult with us.
5. Conclusion
How was the story that included the birth story of the clean paper "Staclean"? I hope you understood why "A4 Blue" is the most widely used in clean paper. I would like to continue introducing the history, uses, and products of clean paper through this column. Thank you for staying with us until the end.
Author Introduction
Yousuke Takatani
Joined Sakurai Corporation in 1992. In my approximately 30 years of company history, I have been involved in clean paper for over 20 years. Currently, I am the head of the Solutions Sales Department.